Braking system



C. C. WH|TTAKER.

BRAKNG SYSTEM. l APPLICATION FILED Nov. 2.9;1920.

1,430,7'11- l Patented 0@I.3,19122.

ATORNEY Patented ct. 3, 1922.

U'NiTED STATES PATENT orifice.

CHAItLES C. 'WI-IITTAKEE, OLE* PITTSBURGH, PEIJNSYLVANA, ASSIGNCR T0 WESTING- HOUSE ELECTRC St MANUFACTURING COMPANY, A CORPORATON OF PENNSYL- VANIA.

BRAKING SYSTEM.

Applcationled November 29, 1920. Serial No. 426,900.

To @ZZ whom it may concern Be it known that I, CHARLES C. WHIT- frairnn, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Braking Systems, of which the following is a specification.

My invention relates to a system of motor control and it has special relation to the electrical braking of vehicle motors and the like. v

One object of my invention is to provide emergency means for effecting connections for electrically braking a motor upon the loss of line power.

`Another object of my invention is toaccomplish the above result in a manner which will be efficient in operation and reliable in service. v

Although the present invention will be described and is shown as a system of control for electrically propelled vehicles, it will be understood that the invention is fully adapted for other uses. Heretofore, electrically-propelled vehicles have been equipped with means for electrically braking the vehicle by some method of regeneration which is adapted for use under conditions wherein the motor may be momentum-driven as, for example, when the vehicle is going down a long or steep grade.

It sometimes occurs that this regenerative braking fails in its purpose because of either failure or loss of line power or other con` ditions. The result is that the air and mechanical brakes of the vehicle are, in that case, insufficient to maintain the vehicle speed below a dangerous value, much less to safely bring the vehicle to a stop when desired.

i The present invention is adaptedto provide means for meeting this emergency by establishing connections which will permit adequate dynamic braking of the vehicle, even thoughthere be a total loss of line power.

My invention may be best understood by reference to the accompanying drawing wherein the single figure is a diagrammatic View of so Vmuch of the circuits and apparatus embodying my invention as are necessary for a complete understanding thereof.

A. vehicle-propelling motor l is shown as having an armature 2 and a held-magnet winding 3, a variable starting resistorl 4 being adapted to be connected in circuit with said armature. The motor is adapted to be energized from a source of energy through a pantograph trolley 5, upon the closure of the customary knife-blade switch (i. The motor circuit includes the coil of an overload relay 7 the main contact members of the line switch 8 and the usual type of reversing switch 20, here shown in a conventional manner.

Upon the completion of the control'circuit to the coil of the line switch' 8, this switch will close and the motor will be energized, with the full resistor 4l in circuit. rlhis resistor is shown as having a pluralT ity `of electromagnetic switches 9 that are adapted to shunt portions of said resistor in a well-known manner s No detailed reference need be made to the master controller or to the main control cir cuits, as they are nota part of the present invention. Also, no reference will be made herein to the preferred form of regenerative braking circuits, as they are fully set forth in a copending application for United States Letters J'Patent of A. J. Hall, P. L. Mardis, and A. Mclver, Serial No. 400,159, filed July so, i920. i

` It will sutlice, for present purposes, to note that the above-noted or other regenerative braking connections may be made; and the present invention is designed not only to secure all ofthe advantagesof this system of control but to add thereto an additional safety feature which will be operableshould regenerative braking` fail for any reason.

Therefore, the present invention contemplates the connection of a pantograph trol- `ley- (in practice, there will usually be more than one), directly to the ground through a conductor 11 and the normally open main contact members of the grounding switch l2. The coil of the grounding switch l2 is adapted to be energized in the following manner lhen the controller for the pantograph trolley (in practice there will usually be one at each end of the vehicle, as shown), is in the cil` position, wherein the trolleys are down or disconnected from theline, a pair of control fingers l() are adapted to be engaged by a contact segment 13 which is mounted upon the drum of the pantograph cont-roller. One ot the control iingers 1t) upon each controller is adapted to be energized through a connection with a positive wire extending` from a battery or other source ci energy to the control iingers of the pantograph controllers.

The auxiliary circuit from either pantograph controller extends through a switch 1.4;, here shown to be a snap switch, but, obviously, any other convenient type of switch may be employed. This switch may be located in a housing having a glass front, so that there will be no opportunity tor the accidental actuation oit this switch by the inctorman, or anyone Assuming new that regenerative braking, lor previously-inentioned reasons, has tailed, tlio motel-man, upon breaking the glass, may turn the key oit the snap switch 14 to close this switch. At the same time, or prior thereto, both the pantograpli controller and the niaster controller (not shown) must be returned to their oit positions, while the reversing switch 2O must be actuated to the reversed position. This condition is obvious, by reason of the fact that, until the master .controller is returned to oit position, to

thereby open the line switch S and close the interlock 19 connected thereto, the actuatingcoil circuit of the switch cannot be completed.

Also, until the pantograph controller is in oil position, the control lingers 10 will not be bridged to permit energization oi the circuit to the coil oi4l the grounding switch 12.

Accordingly, with line switch 8 open,con trol lingers 10 bridged, and snap switch 142 closed, a circuit will be established through the pantograph controller and the snap switch 14, the coil ot the grounding switch 12, conductor 15, and the interlock 19, corresponding` to the open position of the line switch 8, to the negative side ot a battery or other source ot energy. This action will energize the coil of the grounding switch l2, causing it to close to thereby complete the separate grounding circuit lor the disconnected trolley 5 and the lrni'te-blade switch 6.

it the same time, the interlocking segnients located upon this grounding switch will complete a holding circuit for the coil 12 through conductor 16, and also a shunt circuit around the contact members of the overload relay 7 through conductors 17 and 1S. The purpose ot this shunt circuit is to render the overload relay ineffective to intertere with any temporary excessive current which may be required for the entra braking` eiiort, particularly so it thc speed ot 4the -vehicle is high. Consequently, the vehicle will be uninterruptedly bralred and the speed thereof will be maintained below the danger limit.

To start braking. the motorman operates the master controller, whereupon the line the now closed line switch, the resistor 1l, f

used now as a load, the armature 2 and the rerersed series held-magnet winding rl`hus, the closed braking circuit will be conipleted. r'iccordingly, the momentum-driven armature will generate a braking current through. the Variable resistor l, whereby the u'ioi'gorinan will be enabled to control the spe controller, in the customary manner gradually excliule the resistor -l f una. to completely stop the car, :it desired.

hen the vehicle is brought to rest, the snap switch llt may be opened, `which will dfn-ener. e the coil of the grounding switch yed ot the car by inox/'ement ol.: the master to 1.2, .iereoy opening this s 7Vitch and also the f shunt circuit for the orerload relay 7. il pantograph controller may then be moved to cause the trolley 5 engage the trolley wire, as desired, whereupon the motor may be operated in the usual way, upon the manipulation of the master coiitroller.

ilo detailed rcference need be niiade to the manic-st advantages of a method whereby an emergency electrical bi1-airing circuit may be established independent oit any line connections.

l do not wish to be restricted to the specific circuit connections or arrangements ot parts herein "forth, as various modificatiens parting from the spirit and scope olf rny inif'enticn. l desire, therefore, that only7 such limitations shall be imposed as are indicated in the appended claims.

l claim as iny invention 1. ln a system o1c electrical braking for vehicles, the combination with a fnameelectric machine adapted -for regeneration and an overload relay, ot' means tor establishing circuit connect-ions independent ot said overload relay to dynamialla brake said Vehicle upon the :failure of iegeneration.

2. ln a system oil control,

the combination with a source ol energy, a dynamo-electric machine, a starting` resistor and an overload relay, of means adapted to be operated upon the vfailure of said source to render said over load relay ineffective and to connect said motor in circuit with said resistor to electrically brake said motor.

ln a system oi control, the combination with a dynamo-electric machine hz ying a. variable resistor in circuit therewith, and a. line switch adapted to interrupt the motor circuit, ot means adapted to Ahe operatezfl when said line switch open to connect said machine in a circuit including; said resistor to etlect the electrical braking of the machine upon the rcclosure oit said line switch.

thereof may be eltected without del. In a control system for electricallypropelled vehicles, the combination With a dynamo-electric machine, an overload relay, means for connecting said motor to a source of energy, and means adapted to be operated When said connecting means is in off position to reconnect said connecting means and shunt said overload relay to electrically brake said vehicle.

5. In a control system for electrically propelled vehicles, the combination `with a dynamo-electric machine and a line switch adapted to interrupt the motor circuit, of means adapted to be operated When said line f' switch is open, to connect said machine to electrically brake said vehicle, irrespective of the speed of thevehicle, and means for maintaining such operation oit the lirstnamed means after said line switch has been reclosed.

6. In a control system for an electricallypropelled vehicle, the combination Wit-h a supply circuit, a dynamo-electric machine, a current-collecting device for connecting said machine to one conductor of said supply circuit, and a controller for raising and lowering said device, of means operable when said controller is in.ofl7 or dovvn7 position to connect said device to another conductor of said supply circuit and establish other connections for operating said machine to electrically brake said vehicle.

7. In a system of control, the combination with a motor, an overload relay, a line switch having an interlock connection thereupon, and means for connecting said motor to a source, of energy, of a circuit Which includes a grounding switch having interlock connections thereupon and adapted to be closed upon the disconnection of said motorconnecting means,` said circuit further including the line-switch interlock, said grounding switch, When closed, completing a separate grounding circuit for said motorconnecting means and also a shunt circuit for said overload relay through one of the nterlocks on said grounding switc 8. In a vehicle-braking system, the combination with a dynamo-electric machine and a current-collecting` device for the vehicle, or a controller for actuating said device into and out of its operative position, a switch, and means `responsive to certain concurrent operations of said svvitch and said controller for eliecting electrical braking of said machine.

9. In a vehicle-braking system, the combination with a dynamo-electric machine and a current-collecting device for the vehicle, of a controller for actuatingvsaid device into and out of the operative position, asvvitch, and means responsive upon the open-circuiting of said controller and the closure of said switch for effecting electrical braking of said machine.

In testimony whereof, I have hereunto subscribed my name this 22nd day of November, 1920.

CHARLES C. WHITTAKER. 

